Tests for Erection Problems

Test Overview

Tests for erection problems can help find a
cause for a man's problem in having or maintaining an erection (erectile dysfunction, or impotence). Erectile
dysfunction is a common male problem. Most erection problems are caused by a
combination of blood vessel, nerve, or psychological issues.

To
find the cause of erection problems, your doctor will first ask about your
sexual history and do a
physical exam. During the physical exam, the doctor
will:

If the results of your physical exam and other tests are
normal, your doctor may have you try a medicine, such as sildenafil
(for example, Viagra), tadalafil (for example, Cialis), or vardenafil (for example, Levitra), before doing more
tests.

This topic focuses on three more tests you may have after
the physical exam and lab tests listed above. These three specific tests used
to find the cause of erection problems are:

Nocturnal penile tumescence (NPT)
test.

Intracavernosal injection test.

Doppler
ultrasound.

Nocturnal penile tumescence (NPT) test

The NPT
test checks whether a man is having normal erections during sleep. Most men
have 3 to 5 full erections during deep (rapid eye movement, or REM) sleep. Men
who do not have erections because of psychological problems can still have
erections during deep sleep. Occasionally, some sleep problems or serious
depression can prevent these normal nighttime (nocturnal) erections.

This test can be done at home or in a special sleep lab. One of two ways
may be used.

A simple ringlike device called a snap gauge
made up of plastic films is fitted around the penis. The films break at certain
pressures. So an erection during sleep will cause the film to
snap.

An electronic monitoring device records how many, how long, and how
rigid the erections are during sleep. An electronic monitoring device is more expensive than using
the snap gauge, but it is more accurate and gives more detailed information
about erections during sleep.

Tests are usually done for at least two nights in a row.
If good erections occur during sleep, the cause of the erection problems
probably is not physical.

The NPT test may also be called the
stamp test or the rigidity test.

Intracavernosal injection test

During this test,
the doctor injects a medicine (usually alprostadil) into the side of the
penis to make an erection. This is called an intracavernosal injection. A
similar medicine may also be placed into the
urethra, the tube through which urine leaves the
penis. This is called an intraurethral injection. The fullness of the erection
and how long the erection lasts are measured.

Doppler ultrasound test

Doppler ultrasound (also
called color duplex Doppler) uses a handheld tool passed lightly over the
penis. The tool uses reflected sound waves to estimate the speed and direction
of blood as it flows through a blood vessel. The sound waves go to a computer
that changes the sounds to colors that are overlaid on a picture of the blood
vessel. This shows the speed and direction of blood flow. You may need to have medicine injected into your penis (intracavernosal injection) to cause an erection before the Doppler test is done.

The results of your tests may show which kind of treatment is a good choice for you.

Why It Is Done

Tests for erection problems are done
to help find whether the cause of an erection problem is physical,
psychological, or a combination of both.

Physical conditions that
may cause erection problems include:

Problems with the nerves of the penis.
Conditions such as
multiple sclerosis or
diabetes may cause nerve damage that affects a man's
ability to have an erection. Also, surgery, injury, or radiation treatment to
the pelvic area may cause damage to the nerves of the
penis.

Problems with the blood vessels that supply blood to the
penis. Conditions such as hardening of the arteries (atherosclerosis) may make it difficult for a man to
have an erection. Activities such as long-distance bicycle riding on a hard,
narrow saddle may increase a man's risk for having an erection problem.

Psychological tests may be needed if no physical cause is
found for an erection problem. Psychological causes of erection problems may
include:

Anxiety about sexual
performance.

Relationship
problems.

Stress.

Depression or grief.

How To Prepare

Nocturnal penile tumescence (NPT) test

Do not take
any medicines that cause an erection, such as sildenafil (for example, Viagra), tadalafil
(for example, Cialis), and vardenafil (for example, Levitra), before the test.

Do not drink
alcohol or take sleeping pills for 2 days before you have a nocturnal penile
tumescence (NPT) test. The alcohol and the pills can change your deep (REM)
sleep time, which can affect nocturnal erections.

Intracavernosal injection test

If you are having
an intracavernosal injection test, tell your doctor if you:

Doppler ultrasound

You may be asked to avoid
products that contain nicotine (cigarettes, chewing tobacco) for 30 minutes to
2 hours before the test.

How It Is Done

Nocturnal penile tumescence (NPT) test

It is
helpful if you wear briefs-type underwear (not boxer shorts) with a fly front
when you are ready for bed. Put your penis through the fly front and keep your
pubic hair inside the underwear out of the way. Put the device around your
penis. After you put the device on, carefully put your penis inside your
underwear.

The types of devices you can use include:

Snap gauge. A snap
gauge is a ringlike device made up of plastic films that fit around the penis.
The films break at certain pressures. A snap gauge will break during an
erection. It can also tell how firm the penis became during the erection. This
test is usually done 2 or 3 nights in a row.

Electronic devices. Electronic devices measure changes in the
fullness of the penis. The devices have one or more elastic loops that fit
around the penis. These are hooked to a small unit that records changes as the
loops are stretched.

Intracavernosal injection test

The intracavernosal
injection test is generally done by a
urologist in the office or clinic. For this test, you
will need to take off all of your clothes below the waist, and you will be
given a cloth or paper gown to use.

While you sit or stand, your
penis will be cleaned with a special soap. Then your doctor will inject a
medicine into the side of your penis with a small needle. After the medicine is
injected, your doctor may massage the penis for a few seconds to help spread
the medicine in the penis. Some doctors may use a band that is gently tightened
around the base of the penis for 5 minutes after the medicine is given to make
sure an erection occurs.

A low dose of the medicine is used at
first. If the low dose does not cause an erection, then a larger dose may be
used. An erection should occur within 5 to 10 minutes after the medicine is
given.

The medicine may also be given in a thin tablet that is put
in the urethra.

After the medicine is given, you may be asked to
watch sexually stimulating movies or to massage your penis to cause an
erection. Your doctor will measure how rigid and how long the erection lasts.
After the test, your doctor may inject a second medicine to make sure your
erection goes away.

Doppler ultrasound

The Doppler ultrasound test is
done by a urologist or ultrasound technician.

You will lie down on
an examination table. Your doctor may need to inject a medicine or use a soft
band around the penis to cause an erection to see blood flow through the
vessels.

How It Feels

Nocturnal penile tumescence (NPT) test

A nocturnal
penile tumescence (NPT) test does not cause any discomfort, but you may feel
embarrassed about doing the test. Remember that it's important to find the
cause of your inability to have an erection and you don't need to feel
embarrassed about the test.

Intracavernosal injection test

During the
intracavernosal injection test, you will feel a sharp, stinging pain in your penis from the needle. If you feel a burning or aching pain during
the erection, tell your doctor immediately.

Doppler ultrasound

The ultrasound does not cause
any pain. If you get a medicine or device during the test to cause an erection,
you may feel embarrassed and the shot may hurt.

Risks

Nocturnal penile tumescence (NPT) test

There are
no problems from having the nocturnal penile tumescence (NPT) test.

Intracavernosal injection test

The intracavernosal
injection test has a small chance of causing:

Bleeding at the injection
site.

Bruising or swelling around the injection
site.

An erection that lasts for 3 or more hours. This condition,
called priapism, is a rare side effect of some medicines used for this test. If
priapism occurs, it usually can be reversed using another medicine.

Doppler ultrasound

There are no problems from an
ultrasound test. If a device is used to cause an erection, you may have some
mild discomfort. If a shot of medicine is used, you have the same chance for
problems as the intracavernosal injection test.

Results

Tests for erection problems can help
find a cause for a man's problem in having or maintaining an erection (erectile dysfunction, or impotence).

Tests for erection problems may include blood tests for testosterone,
luteinizing hormone, prolactin, and thyroid hormone. A urine test, complete
blood count, blood sugar level, and cholesterol and triglyceride levels may
also be done.

What To Think About

Doppler
ultrasound may not be widely available. To learn more, see the topic
Doppler Ultrasound.

Occasional erection
problems are normal. If you are usually able to have and maintain a full
erection, tests are usually not needed. Your erection problem may be from
stress or anxiety or relationship problems.

Psychological tests may
be recommended if no physical cause is found for your erection problem. You may
want to see a counselor who specializes in sexual problems.

An
angiogram may be recommended if initial tests can't find a cause for your
erection problems. An angiogram is an X-ray test that takes pictures of the
blood flow in an artery. To learn more, see the topic
Angiogram. Experts are not sure how useful the
angiogram test is because treatment to repair the blood vessels of the penis
will be a choice for only a few men with this specific
problem.

Dorsal nerve conduction test, evoked potential studies,
and penile biothesiometry are extensive neurologic tests to check the nerve
supply to the penis. These nervous system tests are not generally done or are
not widely available.

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use.
How this information was developed to help you make better health decisions.